Abstract
The effects of calcitonin (CT), epinephrine and glucagon on the plasma membrane Ca-ATPase activity and the calcium content in the liver were investigated 30min after a single subcutaneous administration of hormones to rats. Ca-ATPase activity in the plasma membrane fraction was significantly decreased by CT (80 MRCmU/100g BW), while it was not significantly lowered by insulin (100mU/100g BW), epinephrine (100μg/100g BW), glucagon (50μg/100g BW), or parathyroid hormone (25U/100g BW). The calcium content in the liver was markedly increased by CT, while it was not significantly elevated by epinephrine or glucagon. Meanwhile, the decrease of Ca-ATPase activity in the plasma membrane fraction produced by CT was significantly prevented by simultaneous administration of epinephrine or glucagon, and also the increase in liver calcium was noticeably interfered with. The present results suggests that the action of CT on liver calcium may differ from that of epinephrine or glucagon which causes an increase in cyclic AMP in the liver cells.
